1. Field of the Invention
The present invention relates to RF signal processing and, more particularly, to a real-time signal rejection circuit that automatically rejects multiple interfering hopping signals while passing a lower level desired signal.
2. Description of the Prior Art
In the field of electronic warfare, it has been the general practice to employ various electronic jamming techniques wherein RF emitters transmit interfering signals at one or more frequencies to obstruct the RF communications of others. Such jamming emitters may be fixed, i.e. transmitting energy at a fixed narrow frequency band, or they may be agile, i.e. transmitting energy at different narrow frequency bands that vary with time (frequency hopping).
To counteract the effects of such jamming, a variety of antijamming devices have been developed. One such device for use with wideband receivers employs a rejection circuit that suppresses one frequency or band of frequencies while passing all other frequencies. One of the most critical problems confronting designers of these rejection circuits for use with wideband receivers in the presence of narrowband interferers has been maintaining sufficient receiver sensitivity so that the power levels of strong interfering signals are significantly reduced while not attenuating a much weaker desired signal. This problem is overcome by the present invention.